A POSSIBLE MOLECULAR STRUCTURAL INDICATOR OF THE LIQUID GLASS-TRANSITION

被引:21
作者
KIVELSON, D [1 ]
STEFFEN, W [1 ]
MEIER, G [1 ]
PATKOWSKI, A [1 ]
机构
[1] MAX PLANCK INST POLYMER RES,W-6500 MAINZ,GERMANY
关键词
D O I
10.1063/1.460990
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
In studying the VH depolarized Rayleigh light-scattering spectrum of orthoterphenyl we have separated an "intermediate" line with almost temperature-independent halfwidth of 50 GHz from both the narrower rotational line with strongly temperature-dependent halfwidth and the broader base line associated with short-range overlap interactions. The integrated intensity I(VH) of the intermediate line decreases by a factor of 25 as the temperature decreases over a range for which the viscosity increases by 11 orders of magnitude. It appears that the extrapolated value of (I(VH)/rho-2)1/2 for this line vanishes as T --> T(o), where rho is the density and T(o) is the ideal liquid-glass transition temperature established by fitting a Vogel-Fulcher relation to the viscosity. We associate this intermediate line with dipole-induced-dipole interactions; its intensity is then given by an equal-time correlation function involving two-, three-, and four-body interactions. Because dipole interactions are quite long range, this correlation function may be a good probe of local molecular order, and I(VH) may thus be a good molecular structural (thermodynamic) indicator (order parameter) of the liquid-glass transition, the first such indicator identified.
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页码:1943 / 1949
页数:7
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